It could be something you are feeding which causes skin problems. Did the kennels feed a different diet. If so perhaps try this diet.
If it was your normal food, it could be an allergy to something where you walk him, or something in your house. Flea bites can cause serious allergies, as been mentioned. But so do the likes of febreze and other household sprays or even washing powder used on the bedding.
You may not find out why the skin was bad before and now improved. I would check with kennels, and look at what is used at home. Then keep

it doesn't return. If it does then you can try to work out the cause from your differences between home and kennels.
Good luck. Skin problems can sometimes be a nightmare to find a cause.
